1. Field of the Invention:
The invention generally relates to a machine for stacking extruded containers having bottoms dimensioned for nested engagement within tops, and particularly relates to a machine for stacking nestable extruded containers where container diameter is greater than container height.
2. Description of the Prior Art:
Cans and containers in which food and other products are packaged are typically shipped in cartons or boxes (cases). Where the diameter or width of the container is greater than its height, the containers (cans) are stacked in two or more levels in a case. Various machines have been developed for stacking such cans and containers for placement in a case.
For example U.S. Pat. No. 2,645,328, F. WINTERS, describes an apparatus for automatically stacking flat cans moving in a single-layer stream on an elevated conveyor into one or more vertical stacks of a pre-determined number of cans on a lower level conveyer. The cans alternately slide down a lower chute for stacking cans at a first position and an upper chute stacking cans at a second position. The lower conveyer incremently advances moving cans stacked at the first position by the lower gravity chute to the second position where cans are stacked by the upper gravity chute on top of the cans previously stacked by the lower chute. Vertical stability of the stacked column of cans is aided by nesting of the bottom of one can into the depressed lid of the can below or above it in the column.
The disadvantages of the apparatus of the type taught by WINTERS, relates to the necessity of maintaining the vertical stability of the stacked columns of cans as they are move downstream on the conveyer system to the point of casing. In particular, during stacking, the preceding column of cans arrests forward travel of each can in order to achieve a vertical column, and after the vertical column is established that column must move adjacent with other columns in rows within chutes having side walls to prevent the column from toppling.
U.S. Pat. No. 3,850,282, CALVERT et al. describes another article stacking mechanism in which a starred wheel receives and translates a container moving in an upper stream sideways into vertical registry over a container moving in a parallel stream below the upper stream. Containers moving in the lower stream are received and held in position by a second starwheel rotating on a common shaft with the first starwheel. Side rails prevent the respective starwheels from toppling the containers as they are received from the conveyers.
In CALVERT it is necessary to both restrain and support the the upper can as it translates sideways to a position vertically above the can in the lower stream. Vertical stability of the stacked containers is aided by nested engagement of the bottom of the upper container within the top of the lower container.